“When you are smiling, the world smiles with you,” as famously sung by the likes of Louis Armstrong, Frank Sinatra, and Nat King Cole. But these famous singers may not have known that those lyrics were backed up by science.
A smile on another person’s face actually triggers a smile on yours too. According to researchers studying the human brain’s amazing ability to read expressions, smiles—and frowns—are so contagious that they can jump from person to person in a fraction of a second.
If someone smiles at you, without even knowing it, you might smile back. What’s happening, researchers say, is that your brain automatically tells your facial muscles to mimic the other person’s expression. And this could help you understand how the other person is feeling.
How does it work?
A recent review published in Trends in Cognitive Sciences states that when human beings see an expression on another face, it activates what is called “sensorimotor simulation”. This sensorimotor automatically mimics the other’s expression, helping us understand and react to the other person’s emotion.
The feeling of smiling, or frowning, reminds you of past experiences making that same facial expression. You might have smiled because you were happy to see a friend. Mimicking another person’s smile reminds you of that happy feeling.
Researchers say that this reaction takes place in the space of a few hundred milliseconds and happens entirely unconsciously. The facial muscles don’t always move, but the relevant parts of the brain are still activated.
Researchers believe that a better understanding of how we “can infer complex mental states from even the slightest facial expression” could help develop new treatments for people with social disorders.